US5051841A - Process for providing digital halftone images with random error diffusion - Google Patents
Process for providing digital halftone images with random error diffusion Download PDFInfo
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- US5051841A US5051841A US07/421,931 US42193189A US5051841A US 5051841 A US5051841 A US 5051841A US 42193189 A US42193189 A US 42193189A US 5051841 A US5051841 A US 5051841A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/40—Picture signal circuits
- H04N1/405—Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels
- H04N1/4051—Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a dispersed dots halftone pattern, the dots having substantially the same size
- H04N1/4052—Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a dispersed dots halftone pattern, the dots having substantially the same size by error diffusion, i.e. transferring the binarising error to neighbouring dot decisions
Definitions
- the present invention generally relates to a method for reproducing images by digital half-toning and, more particularly, to a reproduction method based upon digital halftoning with error diffusion.
- a color-filtered screen is prepared for each of four primary colors. Then the colors are printed sequentially while maintaining precise mechanical registration of the screens.
- Digital halftone printing in contrast to conventional halftone printing, is better suited for shorter production runs.
- the initial step is to scan an image with an optical scanner that detects light intensity values for selected colors. Then for each pixel location, the detected data are converted to gray-scale values to provide a basis for image reproduction. Typically, gray-scale values range from 0 to 255.
- dots are printed in areas corresponding in scale to the original pixel locations.
- the printed dots normally are of fixed size, but their placement and density within the printed areas are varied in accordance with the detected gray-scale values.
- dot density within each printed area determines the spatial resolution and perceived grayness of the area to an observer.
- gray-scale values at detected pixel locations are binary coded.
- the binary coding threshold is 127, i.e., halfway between the minimum and maximum gray-scale values.
- the binary number "1”, for instance, can be assigned to pixel locations where detected gray-scale values are less than 127, and the binary number "0" can be assigned to pixel locations where detected gray-scale values are 127 or more.
- a pixel location with a detected gray-scale value of 100 would be coded as a binary "1".
- a pixel location with a gray-scale value of 145 would be coded as a binary "0".
- a pixel location encoded as a binary "1” generally is black, and a pixel encoded as a binary "0” generally is white.
- the above-described coding techniques for digital halftoning with error diffusion inherently result in coding errors for each pixel location having a gray-scale value other than 0 or 255.
- the magnitude of the coding error resulting from binary encoding a pixel location having a gray-scale value of 100 would be 100 units as measured by gray-scale values.
- the magnitude of the coding error for binary encoding of a pixel location having a gray-scale value of 110 would be 110 units as measured by gray-scale values.
- the present invention provides an improved error diffusion process for eliminating visually-perceptible artifacts in images reproduced by digital halftone printing.
- the error diffusion process includes the steps of:
- e j is the error value diffused to the jth pixel neighbor from the ith pixel location, where the jth pixel neighbor is randomly determined from a predetermined set of pixels neighboring the ith pixel, and where w j is a weighting factor determined for the jth pixel location;
- the predetermined set of neighbor pixels comprises pixels that are immediately adjacent neighbors to a selected ith pixel location. More particularly, it is preferred that the predetermined set of neighbor pixels comprises the pixel that immediately follows a selected ith pixel location, a pixel immediately below the selected ith pixel location, and the pixels that immediately precede and follow the pixel immediately below the selected ith pixel location.
- the weights for the jth and subsequent pixel locations are determined as follows:
- FIG. 1 is a functional block diagram of a digital halftoning system which operates according to the process of the present invention.
- FIG. 2 schematically shows a field of pixels and is offered as an aid to the description of the error diffusion process of the present invention.
- FIG. 1 generally shows a system for digital halftone printing.
- the components of the system comprise an optical image scanner 5, a general purpose digital computer 7, and a digital printer 9.
- the illustrated components are conventional, but by employing the method of the present invention, the components operate in the system to eliminate the appearance of artifacts in images printed by digital halftoning with errordiffusion.
- scanner 5 makes color separations of an image from a medium 13 such as a photographic transparency, a photographic print, or a high-resolution printed original.For each of the separated colors, the picture elements (i.e., pixels) of the original image are digitized to gray-scale values. Then the digitized values are provided to digital computer 7. Within computer 7, the digital information can be processed with conventional graphics software so that images can be retouched, adjusted, recomposed, and so forth. Then the processed images are provided to digital printer 9 for printing onto a sheet 15 by the techniques of conventional digital halftone printing.
- the digital image information that is provided to computer 7 is also binary encoded and then is operated upon according to the halftoning process of the present invention to provide error diffusion prior to printing.
- the object of the error diffusion process of the present invention is to create reproducible images that provide the illusion of a continuous-tone image without discernible artifacts.
- each dot 11 in the field should be understood to represent one pixel location on an image which is presented for optical scanning.
- scanning proceeds from left to right across each pixel row and sequentially, row by row, from the top to the bottom of the field.
- Such a scanning pattern can be described as a raster-type scanning pattern.
- Other scanning patterns might be used; for example, scanning can proceed from left to right across one row of pixels, then in the opposite direction across the next lower row, and so forth in a serpentine pattern.
- each pixel 11 in the field in FIG. 2 can be described by cartesian coordinates; accordingly, an arbitrary pixel "P" is designated as having location (x,y). Because pixel P is in the interior of the field,it has eight immediately-adjacent pixel neighbors. When the pixel field is scanned in a raster-type manner, four of the immediately-adjacent neighboring pixels will be scanned before pixel P, and four will be scanned after pixel P.
- the pixel to the immediate right of pixel P is designated by arrow d 1
- the pixel diagonally below pixel P in the scanning direction is designated by arrow d 2
- the pixel directly below pixel Pis designated by arrow d 3
- the pixel diagonally below pixel P in the direction opposite the scanning direction is designated by the arrow d 4 .
- the pixel designated by arrow d 1 can be described as having cartesian coordinates (x+1,y)
- the pixel designated by arrow d 2 can be described as having coordinates (x+1,y+1).
- the pixel designated by arrow d 3 can be described as having coordinates (x,y+1), and, finally, the pixel designated by arrow d 4 can be described as having coordinates (x-1,y+1).
- the set of directions d 1 through d 4 is herein called the "direction set".
- the error diffusion process of the present invention will be described as beginning at pixel P in FIG. 2. Further forpurposes of discussion, the magnitude of the detected gray-scale value of pixel P will be described as an arbitrary number "z" which is between 0 and 255, inclusive. Still further, the coding error for any pixel locationin the field will be referred to as E x ,y where the subscripts identifythe cartesian coordinates of the pixel.
- the magnitude of the encoding error E x ,y will be a negative number equal to z minus 255 gray-scale units; that is,
- the magnitude of the encoding error is simply equal to the value z in gray-scale units; that is,
- the selected threshold value T is usually a number about midway along the selected gray-scale and typically equals 128. Although the threshold valueusually is held constant, it could be randomly varied, or dithered, in a relatively narrow range about a chosen central value (e.g., 128). In that case, further randomness would be introduced into the error diffusion process that will be described below.
- coding errors are randomly diffused from each given pixel location to four immediately-adjacent neighboring pixel locations that are scanned after the given pixel location. More particularly, for each pixel location from which coding error is diffused, a random choice is made of the order in which errors are to be diffused to the immediately-adjacent neighbors of the pixel location under consideration; that is, the order of directions within the direction set are randomly selected.
- the directions from pixel P to the four immediately-adjacent pixel neighbors that are scanned after pixel P are designated as directions d i , d j , d k , and d l to emphasize that the directions are randomly assigned.
- directions d i , d j , d k , and d l are randomly assigned.
- a first direction d i is assigned aweighting factor w di where the value of the weighting factor is randomly chosen from a uniform distribution of weights between 0.0 and 1.0.
- a second randomly chosen direction d j is assigned a weighting factor w dj where the value of the weighting factor is randomly chosen from a uniform distribution of weights between 0.0 and (1.0-w di ).
- the third randomly selected direction d k is assigned a weighting factor w dk where the value of the weighting factor is randomly chosen from a uniform distribution of weights between 0.0 and (1.0-w di -w dj ).
- pseudo-random weights w di , w dj , w dk , andw dl are used to propagate, or spread, coding errors to the four immediately-adjacent neighbors of each scanned pixel location.
- the propagated error values are designated herein as e 1 , e 2 , e 3 , and e 4 to designate the error values which are distributed to pixel locations (x+1,y), (x+1,y+1), (x,y+1), and (x-1,y+1), respectively.
- weighting factor w di is associated with error e 1
- weighting factor w dj is associated with error e 2
- weighting factor w dk is associated with error e 3
- weighting factor w dl is associated with error e 4 .
- the error values e 1 , e 2 , e 3 , and e 4 can be understood to be pseudo-randomized error values. It should be noted that those propagated error values can beeither positive or negative.
- gray-scale values of pixel located are increased, or decreased.
- the gray-scale value imputed to the location (x+1,y) would be the detected gray-scale value for that location plus the propagated error e 1 .
- the gray-scale value imputed to the pixel located at (x+1,y+1) would be the detected gray-scale value for that pixel location plus the propagated error e 2 .
- the above-described error diffusion process continues for each successively scanned pixel location.
- the gray-scale value for the pixel located at (x+4,y+5) will reflect the error propagated from its neighboring pixels located at (x+3,y+4), (x+4,y+4), (x+5,y+4), and (x+3,y+4).
- the binary coding error propagated from the pixel location (x+4,y+5) will reflect the errors propagated to that location from its set of neighboring pixels, and that error, in turn, will be weighted by the above-described pseudo-random process and then will be diffused to the pixels located at (x+5,y+5), (x+5,y+6), (x+4,y+6), and (x+3,y+6).
- a field such as that shown in FIG. 2 canbe sequentially scanned with different color filters or, alternatively, canbe scanned once with each picture element having multiple exposures, with different filters. Then for each of the selected colors and each of the pixel locations in the scanned field, binary coding errors are diffused asdescribed above. Multi-color images without discernible artifacts can then be printed by conventional digital halftone printing procedures.
- e j is the error value diffused to the jth pixel location from the ith pixel location, where the jth pixel location is randomly determined from the predetermined set of pixels neighboring the ith pixel location, and where w j is the weighting factor determined for the jthpixel location according to the procedures described above;
Abstract
Description
e.sub.j =(w.sub.j)E.sub.i
w.sub.dl =1-w.sub.di -w.sub.dj -w.sub.dk.
E.sub.x,y =z-255 for z≧T.
E.sub.x,y =z for z≦T.
w.sub.di +w.sub.dj +w.sub.dk +w.sub.dl =1.
pixel'.sub.(x+1,y) =pixel.sub.(x+1,y) +e.sub.1
pixel'.sub.(x+1,y+1) =pixel.sub.(x+1,y+1) +e.sub.2
pixel'.sub.(x+1,y+1) =pixel.sub.(x,y+1) +e3 and
pixel'.sub.(x+1,y+1) =pixel.sub.(x-1,y+1) +e.sub.4
e.sub.j =(w.sub.j)E.sub.i
Claims (15)
e.sub.j =(w.sub.j)E.sub.i
w.sub.dl =1-w.sub.di -w.sub.dj -w.sub.dk.
e.sub.j =(w.sub.j)E.sub.i
w.sub.dl =1-w.sub.di -w.sub.dj -w.sub.dk ;
e.sub.1 =(w.sub.di)E.sub.x,y
e.sub.2 =(w.sub.dj)E.sub.x,y
e.sub.3 =(w.sub.dk)E.sub.x,y, and
e.sub.4 =(w.sub.dl)E.sub.x,y ;
pixel'.sub.(x+1,y) =pixel.sub.(x+1,y) +e.sub.1
pixel'.sub.(x+1,y+1) =pixel.sub.(x+1,y+1) +e.sub.2
pixel'.sub.(x,y+1) =pixel.sub.(x,y+1) +e.sub.3 and
pixel'.sub.(x+1,y+1) =pixel.sub.(x-1,y+1) +e.sub.4
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Application Number | Priority Date | Filing Date | Title |
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US07/421,931 US5051841A (en) | 1989-10-16 | 1989-10-16 | Process for providing digital halftone images with random error diffusion |
PCT/US1990/005752 WO1991006172A1 (en) | 1989-10-16 | 1990-10-12 | Process for providing digital halftone images with random error diffusion |
CA 2027790 CA2027790A1 (en) | 1989-10-16 | 1990-10-16 | Process for providing digital halftone images with random error diffusion |
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US07/421,931 US5051841A (en) | 1989-10-16 | 1989-10-16 | Process for providing digital halftone images with random error diffusion |
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US07/509,602 Continuation-In-Part US5107346A (en) | 1988-10-14 | 1990-04-13 | Process for providing digital halftone images with random error diffusion |
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Cited By (15)
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US5260807A (en) * | 1992-06-05 | 1993-11-09 | Eastman Kodak Company | Method and apparatus for imbedding controlled structure for gray scale rendering |
US5260810A (en) * | 1990-11-16 | 1993-11-09 | Kabushiki Kaisha Toshiba | Image processing apparatus with improved dithering scheme |
DE19511417A1 (en) * | 1994-04-15 | 1995-12-07 | Fuji Photo Film Co Ltd | Method and device for binary conversion of an image signal |
US5515456A (en) * | 1993-10-26 | 1996-05-07 | Visual Edge Technology, Inc. | Process for providing digital halftone image with random error diffusion, color correction and enlargement |
US5534945A (en) * | 1994-12-16 | 1996-07-09 | International Business Machines Corporation | System and method for providing black diffusion in video image processing |
US5539667A (en) * | 1992-09-15 | 1996-07-23 | Gcc Technologies | Method and apparatus for improved digital film recorder |
US5592592A (en) * | 1994-07-01 | 1997-01-07 | Seiko Epson Corporation | Method and apparatus for minimizing artifacts in images produced by error diffusion halftoning utilizing ink reduction processing |
US5611022A (en) * | 1993-07-07 | 1997-03-11 | Dataproducts Corporation | Color imaging |
US5835687A (en) * | 1996-10-21 | 1998-11-10 | Vidar Systems Corporation | Methods and apparatus for providing digital halftone images with random error diffusion dithering |
US20030090729A1 (en) * | 2001-10-01 | 2003-05-15 | Xerox Corporation | Rank-order error diffusion image processing |
US20030182341A1 (en) * | 2002-03-20 | 2003-09-25 | Microsoft Corporation. | Systems and methods for diffusing clipping error |
US20030206662A1 (en) * | 2002-05-03 | 2003-11-06 | Avinash Gopal B. | Method and apparatus for improving perceived digital image quality |
US20040181727A1 (en) * | 2003-02-27 | 2004-09-16 | Ballard Paul N. | Overflow error diffusion |
US20040207879A1 (en) * | 2003-04-16 | 2004-10-21 | Bailey James Ray | Systems and methods for error diffusion |
US20040257623A1 (en) * | 2003-06-23 | 2004-12-23 | Konica Minolta Business Technologies, Inc. | Image processing apparatus and method |
Citations (39)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3977007A (en) * | 1975-06-02 | 1976-08-24 | Teletype Corporation | Gray tone generation |
US4032978A (en) * | 1975-01-20 | 1977-06-28 | International Business Machines Corporation | Pseudo halftone print generator and method |
US4280144A (en) * | 1979-12-03 | 1981-07-21 | International Business Machines Corporation | Coarse scan/fine print algorithm |
US4339774A (en) * | 1979-12-20 | 1982-07-13 | Cambridge Consultants Limited | Apparatus and method for generating a dispersed dot half tone picture from a continuous tone picture |
US4345313A (en) * | 1980-04-28 | 1982-08-17 | Xerox Corporation | Image processing method and apparatus having a digital airbrush for touch up |
US4393452A (en) * | 1979-06-02 | 1983-07-12 | Ricoh Co., Ltd. | Method of reproducing a picture having improved resolution |
US4449150A (en) * | 1981-01-19 | 1984-05-15 | Ricoh Company, Ltd. | Method of processing medium tone picture |
US4470065A (en) * | 1982-03-25 | 1984-09-04 | Rca Corporation | Adaptive error concealment using horizontal information determination from adjacent lines |
US4544922A (en) * | 1981-10-29 | 1985-10-01 | Sony Corporation | Smoothing circuit for display apparatus |
US4569081A (en) * | 1983-12-30 | 1986-02-04 | International Business Machines Corporation | Method for expansion of a digital image |
US4578713A (en) * | 1984-07-20 | 1986-03-25 | The Mead Corporation | Multiple mode binary image processing |
US4587621A (en) * | 1982-03-08 | 1986-05-06 | The Mead Corporation | Device for electrical variable magnification of document image |
US4595948A (en) * | 1982-10-13 | 1986-06-17 | Ricoh Company, Ltd. | Multicolor ink jet recording apparatus having means for preventing blurring of ink |
US4610026A (en) * | 1982-04-30 | 1986-09-02 | Hitachi, Ltd. | Method of and apparatus for enlarging/reducing two-dimensional images |
US4611349A (en) * | 1984-08-13 | 1986-09-09 | Xerox Corporation | Halftone image scaling |
US4616268A (en) * | 1983-06-20 | 1986-10-07 | Dainippon Screen Mfg. Co., Ltd. | Method and system for increasing use efficiency of a memory of an image reproducing system |
US4628534A (en) * | 1984-07-06 | 1986-12-09 | Honeywell Information Systems Inc. | Method for changing the resolution of compressed image data |
US4631751A (en) * | 1984-10-24 | 1986-12-23 | Anderson Karen L | Method for enlarging a binary image |
US4633503A (en) * | 1984-03-19 | 1986-12-30 | The United States Of America As Represented By The Secretary Of The Navy | Video zoom processor |
US4635078A (en) * | 1983-04-28 | 1987-01-06 | Canon Kabushiki Kaisha | Intermediate gradient image producing method |
US4651287A (en) * | 1984-06-14 | 1987-03-17 | Tsao Sherman H | Digital image processing algorithm for output devices with discrete halftone gray scale capability |
US4654721A (en) * | 1985-04-12 | 1987-03-31 | International Business Machines Corporation | System for reproducing multi-level digital images on a bi-level printer of fixed dot size |
US4656664A (en) * | 1984-10-24 | 1987-04-07 | International Business Machines Corporation | Method for reducing a binary image |
US4661987A (en) * | 1985-06-03 | 1987-04-28 | The United States Of America As Represented By The Secretary Of The Navy | Video processor |
US4673971A (en) * | 1984-07-12 | 1987-06-16 | Dainippon Screen Mfg. Co., Ltd. | Halftone dot formation |
US4680645A (en) * | 1986-08-25 | 1987-07-14 | Hewlett-Packard Company | Method for rendering gray scale images with variable dot sizes |
US4686580A (en) * | 1983-02-10 | 1987-08-11 | Canon Kabushiki Kaisha | Method and apparatus for changing image size |
US4700235A (en) * | 1983-11-14 | 1987-10-13 | Dr. Ing. Rudolf Hell Gmbh | Method and apparatus for producing half-tone printing forms with rotated screens on the basis of randomly selected screen threshold values |
US4733230A (en) * | 1984-09-06 | 1988-03-22 | Hitachi, Ltd. | Method of displaying continuous tone picture using limited number of different colors or black-and-white levels, and display system therefor |
US4734786A (en) * | 1983-10-17 | 1988-03-29 | Canon Kabushiki Kaisha | Image processing apparatus |
US4736254A (en) * | 1984-11-22 | 1988-04-05 | Matsushita Electric Industrial Co., Ltd. | Method and apparatus for generating pseudo-halftone dots by comparing gray scale values of an original with dither threshold values stored in cells of a matrix array divided into imaginary matrices of elemental areas each containing one cell |
US4742400A (en) * | 1986-02-12 | 1988-05-03 | Ricoh Corporation | Digital image processing device for intermediate tone |
US4752822A (en) * | 1983-03-08 | 1988-06-21 | Canon Kabushiki Kaisha | Color halftone image processing apparatus producing various screen angles and having an adaptive color image data conversion look-up table and a small-capacity masking memory |
US4771473A (en) * | 1985-05-22 | 1988-09-13 | Minolta Camera Kabushiki Kaisha | Image reader having electrical and optical means for varying magnification |
US4890167A (en) * | 1986-10-17 | 1989-12-26 | Matsushita Electric Industrial Co., Ltd. | Apparatus for processing image signal |
US4891714A (en) * | 1989-04-24 | 1990-01-02 | Eastman Kodak Company | Apparatus for non-linear error diffusion thresholding of multilevel video images |
US4924322A (en) * | 1988-03-18 | 1990-05-08 | Matsushita Electric Industrial Co., Ltd. | Bi-level image display signal processing apparatus |
US4958238A (en) * | 1988-03-08 | 1990-09-18 | Canon Kabushiki Kaisha | Image processing method and apparatus with conditional correction of error data |
US4969052A (en) * | 1988-05-11 | 1990-11-06 | Canon Kabushiki Kaisha | Image processing method and apparatus |
-
1989
- 1989-10-16 US US07/421,931 patent/US5051841A/en not_active Expired - Fee Related
Patent Citations (39)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4032978A (en) * | 1975-01-20 | 1977-06-28 | International Business Machines Corporation | Pseudo halftone print generator and method |
US3977007A (en) * | 1975-06-02 | 1976-08-24 | Teletype Corporation | Gray tone generation |
US4393452A (en) * | 1979-06-02 | 1983-07-12 | Ricoh Co., Ltd. | Method of reproducing a picture having improved resolution |
US4280144A (en) * | 1979-12-03 | 1981-07-21 | International Business Machines Corporation | Coarse scan/fine print algorithm |
US4339774A (en) * | 1979-12-20 | 1982-07-13 | Cambridge Consultants Limited | Apparatus and method for generating a dispersed dot half tone picture from a continuous tone picture |
US4345313A (en) * | 1980-04-28 | 1982-08-17 | Xerox Corporation | Image processing method and apparatus having a digital airbrush for touch up |
US4449150A (en) * | 1981-01-19 | 1984-05-15 | Ricoh Company, Ltd. | Method of processing medium tone picture |
US4544922A (en) * | 1981-10-29 | 1985-10-01 | Sony Corporation | Smoothing circuit for display apparatus |
US4587621A (en) * | 1982-03-08 | 1986-05-06 | The Mead Corporation | Device for electrical variable magnification of document image |
US4470065A (en) * | 1982-03-25 | 1984-09-04 | Rca Corporation | Adaptive error concealment using horizontal information determination from adjacent lines |
US4610026A (en) * | 1982-04-30 | 1986-09-02 | Hitachi, Ltd. | Method of and apparatus for enlarging/reducing two-dimensional images |
US4595948A (en) * | 1982-10-13 | 1986-06-17 | Ricoh Company, Ltd. | Multicolor ink jet recording apparatus having means for preventing blurring of ink |
US4686580A (en) * | 1983-02-10 | 1987-08-11 | Canon Kabushiki Kaisha | Method and apparatus for changing image size |
US4752822A (en) * | 1983-03-08 | 1988-06-21 | Canon Kabushiki Kaisha | Color halftone image processing apparatus producing various screen angles and having an adaptive color image data conversion look-up table and a small-capacity masking memory |
US4635078A (en) * | 1983-04-28 | 1987-01-06 | Canon Kabushiki Kaisha | Intermediate gradient image producing method |
US4616268A (en) * | 1983-06-20 | 1986-10-07 | Dainippon Screen Mfg. Co., Ltd. | Method and system for increasing use efficiency of a memory of an image reproducing system |
US4734786A (en) * | 1983-10-17 | 1988-03-29 | Canon Kabushiki Kaisha | Image processing apparatus |
US4700235A (en) * | 1983-11-14 | 1987-10-13 | Dr. Ing. Rudolf Hell Gmbh | Method and apparatus for producing half-tone printing forms with rotated screens on the basis of randomly selected screen threshold values |
US4569081A (en) * | 1983-12-30 | 1986-02-04 | International Business Machines Corporation | Method for expansion of a digital image |
US4633503A (en) * | 1984-03-19 | 1986-12-30 | The United States Of America As Represented By The Secretary Of The Navy | Video zoom processor |
US4651287A (en) * | 1984-06-14 | 1987-03-17 | Tsao Sherman H | Digital image processing algorithm for output devices with discrete halftone gray scale capability |
US4628534A (en) * | 1984-07-06 | 1986-12-09 | Honeywell Information Systems Inc. | Method for changing the resolution of compressed image data |
US4673971A (en) * | 1984-07-12 | 1987-06-16 | Dainippon Screen Mfg. Co., Ltd. | Halftone dot formation |
US4578713A (en) * | 1984-07-20 | 1986-03-25 | The Mead Corporation | Multiple mode binary image processing |
US4611349A (en) * | 1984-08-13 | 1986-09-09 | Xerox Corporation | Halftone image scaling |
US4733230A (en) * | 1984-09-06 | 1988-03-22 | Hitachi, Ltd. | Method of displaying continuous tone picture using limited number of different colors or black-and-white levels, and display system therefor |
US4631751A (en) * | 1984-10-24 | 1986-12-23 | Anderson Karen L | Method for enlarging a binary image |
US4656664A (en) * | 1984-10-24 | 1987-04-07 | International Business Machines Corporation | Method for reducing a binary image |
US4736254A (en) * | 1984-11-22 | 1988-04-05 | Matsushita Electric Industrial Co., Ltd. | Method and apparatus for generating pseudo-halftone dots by comparing gray scale values of an original with dither threshold values stored in cells of a matrix array divided into imaginary matrices of elemental areas each containing one cell |
US4654721A (en) * | 1985-04-12 | 1987-03-31 | International Business Machines Corporation | System for reproducing multi-level digital images on a bi-level printer of fixed dot size |
US4771473A (en) * | 1985-05-22 | 1988-09-13 | Minolta Camera Kabushiki Kaisha | Image reader having electrical and optical means for varying magnification |
US4661987A (en) * | 1985-06-03 | 1987-04-28 | The United States Of America As Represented By The Secretary Of The Navy | Video processor |
US4742400A (en) * | 1986-02-12 | 1988-05-03 | Ricoh Corporation | Digital image processing device for intermediate tone |
US4680645A (en) * | 1986-08-25 | 1987-07-14 | Hewlett-Packard Company | Method for rendering gray scale images with variable dot sizes |
US4890167A (en) * | 1986-10-17 | 1989-12-26 | Matsushita Electric Industrial Co., Ltd. | Apparatus for processing image signal |
US4958238A (en) * | 1988-03-08 | 1990-09-18 | Canon Kabushiki Kaisha | Image processing method and apparatus with conditional correction of error data |
US4924322A (en) * | 1988-03-18 | 1990-05-08 | Matsushita Electric Industrial Co., Ltd. | Bi-level image display signal processing apparatus |
US4969052A (en) * | 1988-05-11 | 1990-11-06 | Canon Kabushiki Kaisha | Image processing method and apparatus |
US4891714A (en) * | 1989-04-24 | 1990-01-02 | Eastman Kodak Company | Apparatus for non-linear error diffusion thresholding of multilevel video images |
Non-Patent Citations (2)
Title |
---|
IBM Technical Disclosure Bulletin, vol. 23, No. 10, issued Mar. 1981, (S. J. Fox et al.), "Multiple Error Correction Algorithm for Halftone, Continuous Tone and Text Reproduction". |
IBM Technical Disclosure Bulletin, vol. 23, No. 10, issued Mar. 1981, (S. J. Fox et al.), Multiple Error Correction Algorithm for Halftone, Continuous Tone and Text Reproduction . * |
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